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🐛 Fix AVR maths used by Stepper (#25338)

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tombrazier 2023-02-21 22:37:11 +00:00 committed by GitHub
parent 464bb1f149
commit 5a8883b44f
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3 changed files with 24 additions and 22 deletions
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40
Marlin/src/HAL/AVR/math.h
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@ -27,13 +27,14 @@
// intRes = longIn1 * longIn2 >> 24
// uses:
// A[tmp] to store 0
// B[tmp] to store bits 16-23 of the 48bit result. The top bit is used to round the two byte result.
// note that the lower two bytes and the upper byte of the 48bit result are not calculated.
// this can cause the result to be out by one as the lower bytes may cause carries into the upper ones.
// B A are bits 24-39 and are the returned value
// C B A is longIn1
// D C B A is longIn2
// r1, r0 for the result of mul.
// [tmp1] to store 0.
// [tmp2] to store bits 16-23 of the 56 bit result. The top bit of [tmp2] is used for rounding.
// Note that the lower two bytes and the upper two bytes of the 56 bit result are not calculated.
// This can cause the result to be out by one as the lower bytes may cause carries into the upper ones.
// [intRes] (A B) is bits 24-39 and is the returned value.
// [longIn1] (C B A) is a 24 bit parameter.
// [longIn2] (D C B A) is a 32 bit parameter.
//
FORCE_INLINE static uint16_t MultiU24X32toH16(uint32_t longIn1, uint32_t longIn2) {
uint8_t tmp1;
@ -66,11 +67,9 @@ FORCE_INLINE static uint16_t MultiU24X32toH16(uint32_t longIn1, uint32_t longIn2
A("add %[tmp2], r1")
A("adc %A[intRes], %[tmp1]")
A("adc %B[intRes], %[tmp1]")
A("lsr %[tmp2]")
A("adc %A[intRes], %[tmp1]")
A("adc %B[intRes], %[tmp1]")
A("mul %D[longIn2], %A[longIn1]")
A("add %A[intRes], r0")
A("lsl %[tmp2]")
A("adc %A[intRes], r0")
A("adc %B[intRes], r1")
A("mul %D[longIn2], %B[longIn1]")
A("add %B[intRes], r0")
@ -85,11 +84,16 @@ FORCE_INLINE static uint16_t MultiU24X32toH16(uint32_t longIn1, uint32_t longIn2
return intRes;
}
// intRes = intIn1 * intIn2 >> 16
// intRes = intIn1 * intIn2 >> 8
// uses:
// r26 to store 0
// r27 to store the byte 1 of the 24 bit result
FORCE_INLINE static uint16_t MultiU16X8toH16(uint8_t charIn1, uint16_t intIn2) {
// r1, r0 for the result of mul. After the second mul, r0 holds bits 0-7 of the 24 bit result and
// the top bit of r0 is used for rounding.
// [tmp] to store 0.
// [intRes] (A B) is bits 8-15 and is the returned value.
// [charIn1] is an 8 bit parameter.
// [intIn2] (B A) is a 16 bit parameter.
//
FORCE_INLINE static uint16_t MultiU8X16toH16(uint8_t charIn1, uint16_t intIn2) {
uint8_t tmp;
uint16_t intRes;
__asm__ __volatile__ (
@ -97,10 +101,8 @@ FORCE_INLINE static uint16_t MultiU16X8toH16(uint8_t charIn1, uint16_t intIn2) {
A("mul %[charIn1], %B[intIn2]")
A("movw %A[intRes], r0")
A("mul %[charIn1], %A[intIn2]")
A("add %A[intRes], r1")
A("adc %B[intRes], %[tmp]")
A("lsr r0")
A("adc %A[intRes], %[tmp]")
A("lsl r0")
A("adc %A[intRes], r1")
A("adc %B[intRes], %[tmp]")
A("clr r1")
: [intRes] "=&r" (intRes),

2
Marlin/src/module/stepper.cpp
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@ -2062,7 +2062,7 @@ uint32_t Stepper::calc_timer_interval(uint32_t step_rate) {
const uint8_t rate_mod_256 = (step_rate & 0x00FF);
const uintptr_t table_address = uintptr_t(&speed_lookuptable_fast[uint8_t(step_rate >> 8)][0]),
gain = uint16_t(pgm_read_word(table_address + 2));
return uint16_t(pgm_read_word(table_address)) - MultiU16X8toH16(rate_mod_256, gain);
return uint16_t(pgm_read_word(table_address)) - MultiU8X16toH16(rate_mod_256, gain);
}
else { // lower step rates
uintptr_t table_address = uintptr_t(&speed_lookuptable_slow[0][0]);

4
Marlin/src/module/stepper.h
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@ -114,11 +114,11 @@
#define TIMER_READ_ADD_AND_STORE_CYCLES 13UL
// The base ISR
#define ISR_BASE_CYCLES 1000UL
#define ISR_BASE_CYCLES 996UL
// Linear advance base time is 32 cycles
#if ENABLED(LIN_ADVANCE)
#define ISR_LA_BASE_CYCLES 32UL
#define ISR_LA_BASE_CYCLES 30UL
#else
#define ISR_LA_BASE_CYCLES 0UL
#endif